Knavery's plain face is never seen till us'd

"Make the Moor thank me, love me, reward me,
For making him egragiously an ass,
And practising upon his peace and quiet
Even to madness. 'Tis here, but yet confus'd;
Knavery's plain face is never seen till us'd"

Iago
Act 2 i. 297-301

I Will Have my Revenge

Othello you have done me wrong,"Preferment goes by letter and affection, not by the old gradation,where each second stood heir to the first. Now sir, be judge yourself whether I in any just term am affin'd to love the Moor" How dare you not go with the order which is accustomed to the military. You have done me wrong, now I will do wrong to you but "too early seen unknown, and known too late!"  Chaos will ensue.

Iago to Roderigo
Act 1 i. 36-40